mushroom supplement added to casing to improve postharvest ... · this project was done to study...

240 E u r o p e a n J o u r n a l o f H o r t i c u l t u r a l S c i e n c e

Eur. J. Hortic. Sci. 80(5), 240–248 | ISSN 1611-4426 print, 1611-4434 online | http://dx.doi.org/10.17660/eJHS.2015/80.5.6 | © ISHS 2015

Mushroom supplement added to casing to improve postharvest quality of white button mushroomM. Adibian1 and Y. Mami2

1 Higher Educational Complex of Saravan, Iran2 Department of Horticulture Science, Faculty of Agriculture, University of Guilan, Iran

Original article

Significance of this studyWhat is already known on this subject?• Supplementation at casing to increase postharvest

quality was a suitable practice in production of Agaricus bisporus. This is due to extra nutrition provided by supplements at this stage is directly utilized by mushroom mycelia for increased quality. The carbon units supplied to the compost in oil sup-plementation of the compost at casing were utilized to synthesize mannitol and fatty acids.

What are the new findings?• Supplementing with 34 g soybean and 51 g corn

improved some quality indices of A. bisporus more than control and other treatments. Mushrooms sup-plemented with 51 g soybean and corn appeared to have higher L* values.

What is the expected impact on horticulture?• Supplementing substrate at casing is a relatively

easy and low-cost cultural practice that may be suc-cessfully used to enhance yields, BE, nutritive values, post-harvest quality and maximize utilization of substrate.

SummaryThis project was done to study the effects of

supplementing casing with ground corn and soybean seed applied at: 0 (control), 17, 34 and 51 g per 5 kg peat on color, weight loss, electrolyte leakage rate, total soluble solids, vitamin C, total phenol and antioxidant capacity of Agaricus bisporus. There were significant differences between supplemented and non-supplemented casings. Analyses of phenolic compounds revealed that mushrooms grown on casing supplemented with corn at 51 g per 5 kg peat contained more phenols than other treatments. The lowest amount of antioxidants in mushrooms was observed in the control. In addition, treatment of 51 g per 5 kg soybean and corn caused the highest total soluble solids. The color parameters for the color change of the materials were quantified by the hunter L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) system. There were significant differences in mushrooms L*, a* and b* values in storage times of 8, 12 and 16 days among different supplements. Mushrooms supplemented with 51 g soybean and corn appeared to have higher L* values compared with other treatments. Amounts of protein content, electrolyte leakage, vitamin C and weight loss were significant if levels go up or down with storage time. The highest vitamin C, protein and antioxidant capacity were obtained with 34 and 51 g soybeans and 34 g corn, respectively. Results suggest that adding supplements in the casing increased the nutritional quality and shelf-life of mushrooms.

KeywordsAgaricus bisporus, compost, corn, shelf-life, soybean

IntroductionThe button mushroom [Agaricus bisporus (Lange) Sing]

is the most widely cultivated and consumed mushroom throughout the world and includes about 40% of total world mushroom production (Giri and Prasad, 2007). The casing layer, applied 14–16 days after spawning is an es-sential part of the total substrate in the artificial culture of A. bisporus. Although many different materials may func-tion as a casing layer, peat is generally regarded as the most suitable. Because of its unique water holding and structural properties, it is widely accepted as an ideal for casing (Eger, 1972; Hayes, 1981). Peat has a neutral pH and because of its organic content and granular structure, stays porous even

after a succession of watering, holds moisture, allows ap-propriate gaseous exchanges and supports microbial pop-ulation able to release hormone-like substances which are likely involved in stimulating the initiation of fruit bodies (Eger, 1972; Hayes, 1981). Gerrits (1986) found that sup-plementation at casing was better than at spawning. This is probably due to extra nutrition provided by supplements at this stage is directly utilized by mushroom mycelia for increased yield and quality. Supplementation at spawning is generally associated with rise in temperature and inci-dence of weed moulds, which may jeopardize yield (Dhar and Kapoor, 1990; Vijay and Gupta, 1992). The production and fresh use of button mushroom in Iran have increased rapidly during the last decade. However, the highly perish-able nature of mushrooms remains a problem for the prog-ress of this industry (Beaulieu et al., 1992; Gautam et al., 1998). In fact, fresh mushrooms can only be stored for a few days until they lose freshness and quality. There are many methods to extend the shelf-life of mushrooms. They include modified atmosphere packaging (MAP) (Roy et al., 1995), controlled atmosphere storage (CA) (Lopez-Briones et al., 1992), coating (Nussinovitch and Kampf, 1993), re-frigeration (Gormley, 1975; Mau et al., 1993), cultivating with CaCl2 solution (Miklus and Beelman, 1996) and using sorbitol (Roy et al., 1995). Most methods mentioned are

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Adibian and Mami | Supplementation at casing to improve postharvest quality of white button mushroom

used at postharvest period. A low-cost and easy practice that can be used at pre-harvest is supplementing at casing with lipo-protein supplements. Sporophore growth prior to harvest is sustained by nutrients and water from the compost, and casing material. When the sporophore is harvested and the nutrient and water supply are cut off, its metabolism adapts to sustain gill growth and spore pro-duction. There have been relatively few areas of investiga-tion into mushroom postharvest physiology, two of which, carbon and nitrogen metabolism are concerned with nutri-ents and their redistribution. Hammond (1979) mentioned that during 4 days storage at 18°C mannitol levels in intact sporophores fall from 24.5 to 4% and glycogen levels fall from 11.8 to 4.5%. These compositional changes are not uniform throughout the sporophore. While mannitol level in the pileus and cap fall during postharvest storage, a peak in the mannitol concentration occurs in the stipe after 2 days followed by a decline. Levels of trehalose and glucose within the stipe of stored mushrooms also peak at the same time as mannitol (Hammond and Nichols, 1975).

Experiments using radiolabeled linoleic acid showed that the carbon units supplied to the compost in oil sup-plementation of the compost at casing were utilized to syn-thesize mannitol and fatty acids (Holtz and Schisler, 1986). Protein is the main source of nitrogen for redistribution after harvest. The level of soluble protein in sporophore tissues decreases during postharvest storage of A. bisporus and A. bitorquis (Burton et al., 1993). After 5 days storage at 18°C, the soluble protein level falls to 30–70% of that in freshly harvested sporophores. Levels of chitin, urea and cell wall associated protein were shown to increase after harvest (Hammond, 1979).

The aim of this study is to evaluate the effect of ground corn and soybean seed as rich sources of protein and oil applied to casing on post-harvest quality of white button mushroom.

Materials and methodsThe experiments were conducted in the Agricultural

Faculty of the University of Guilan; Rasht, Iran, in 2013–2014. The experiment was set up in a Split Plot in Time (SP-T) design with 3 replications. Measurements were made during 1st, 4th, 8th, 12th and 16th day for the mushrooms stored continuously at 4°C and 80% relative humidity.

Compost, casing soil and supplement preparationCompost bags (60x40x10 cm) containing 17 kg of com-

post derived from wheat straw and 5 kg peat (as casing soil) were purchased locally (Bibi, Karaj, Iran). Compost was analyzed for chemical properties prior to use (Table 1). Corn (CR) and soybean (SB) seeds were purchased lo-cally. Seed were ground (0.5 mm screen) and autoclaved in bags (high density polyethylene bags, 30–40 cm) at 110°C (pressure 70 kPa) for 15 min. This material was mixed with peat at 0, 17, 34 and 51 g per 5 kg peat prior to application as casing. Supplements were analyzed for nitrogen amounts prior to use (Table 2).

Adjusting the environmental conditionsThe optimum conditions provided for spawn run in a room were 23±1°C (air), RH 90% and a CO2 level of 12,000–15,000 µg L-1. The temperature at case run, one stage before crop initiation (up to 1 week after casing) was 24±1°C (air), RH 95% and CO2 level of 7,500 ppm, and after an additional week it changed to 15–17°C (air), RH to 85% and CO2 level

of 800–1,000 ppm by providing 6 air changes of 10–15 min-utes per day.

CasingAfter completion of mycelium running, the open top of

the spawn bags were covered with 4 cm of pasteurized cas-ing (peat + supplement). Watering after casing was done as suggested for commercial growth (Randle, 1984; Shandi-lya, 1986).

Cropping and harvestingAfter completion of mycelium running in the casing soil,

bags were cooled to 16°C and maintained at this tempera-ture and a relative humidity above 80%. Sporophores were harvested before the fruiting body showed veil opening of the cap from the stipe.

Color measurementsSample color was measured at specified time intervals

during storage period by a model colorimeter (Minolta CR-400, Japan). In this system of color representation the values L*, a* and b* describe a uniform three-dimensional color space, where the L* value corresponds to a dark-bright scale, a* is negative for green and positive for red, whereas b* is negative for blue and positive for yellow. The colorimeter was calibrated using a standard white plate under normal light conditions.

Weight loss Weight loss during postharvest storage was deter-

mined by periodical weighing, and calculated by dividing the weight change during storage by the original weight:

Weight loss (%) = [(Wi-Ws)/Wi] × 100

where Wi = initial weight and Ws = weight at sampling period.

Electrolyte leakage rate Electrolyte leakage rate was measured essentially as

described by Autio et al. (1986). A. bisporus fruit bodies (5 g) were cut into four pieces, leaving the pileus intact and suspended in 40 mL of deionized water in a 100 mL beaker. Electrical conductivity was measured immediately (P0) and again after 10 min (P1). Samples were then boiled for 10 min and cooled to room temperature, and a final con-ductivity measurement (P2) was taken. The relative elec-

Table 1. Compost analysis.

OM 71% (w/w)NH4 0.007%C 40.5%N 2.3%C/N 17.6%pH 6.8

Table 2. Supplement nitrogen content.

Supplement N (%)Corn (CR) 4.05Soybean (SB) 7.76




trolyte leakage rate (RELT) was calculated according to the following equation: (P1 - P0)/ (P2 - P0) and expressed as a percentage.

Total soluble solids (TSS)TSS is an index of soluble solids concentration. Homo-

genated ground sporophore tissue was filtered through the filter paper Whatman No. 1 by means of vacuum and the total soluble solid of the flow throughout the process was determined by a digital refractometer ATAGO PR-32α (AT-AGO, USA Inc., Kirkland, WA). The results were expressed as g per 100 g FW.

Vitamin C contentVitamin C was determined by the 2, 6-dichloro-

phenol-indophenol titration method, in which the dye is re-duced by ascorbic acid, resulting in disappearance of the color (AOAC, 2002). Mushroom fresh tissue (3 g) was mixed with 20 mL (3%) metaphosphoric acid and thereafter was homogenized. Then ascorbic acid was determined by titra-tion of 15 mL filtrated juice by DIP containing bicarbonate sodium an expressed by mg ascorbic acid per 100 g FW.

Protein contentProtein content was determined by the method of

Bradford (1976) using bovine serum albumin as the stan-dard. An amount of 2 g of mushroom samples were cut into pieces with a scissor and grinded in mortar with 5 mL of phosphate buffer (pH 7.6) and was then transformed to the centrifuge tubes. The homogenate was centrifuged at 14,000 rpm for 20 minutes. The supernatant of different mushroom samples were put in separate tubes. The vol-ume of all of the samples in tubes were then made equal by adding phosphate buffer solution and the extractions were stored in the refrigerator at 4°C for further analysis. The absorbance of blue color was read at 595 nm using uv-visi-ble spectrophotometer model PG Instrument +80, England. The amount of protein was quantified by using a standard curve and results were expressed as mg protein per 100 g fresh weight of mushrooms.

Total phenolic compounds Amounts of total phenolic compounds in fresh mush-rooms were determined according to the Folin-Ciocalteu procedure (Singleton et al., 1990) with some modifications. For this purpose, 0.5 g mushroom slices was ground in the presence of liquid nitrogen by mortar and pestle, then 10 mL pure methanol was added to it for extracting phenolic compounds. The extract was centrifuged with 3,000 rpm for 15 min at 4°C with an AVANTI™ J-25 centrifuge (Beckman Instruments Inc., Fullerton, CA) and then filtered through a Whatman No. 1 filter paper. Then 300 µL of methanolic ex-tract was brought to a volume of 500 µL with distilled water into test tubes, followed by 2.5 mL of 10% Folin-Ciocalteu reagent and allowed to stand for 6 min. Thereafter, 2 mL of 7.5% sodium carbonate solution were added. Each sample was allowed to stand for 90 min at room temperature in darkness and the absorbance was measured at 760 nm us-ing an UV/Vis spectrophotometer model PG Instrument + 80, (Leicester, UK). Phenolic content was expressed as mg gallic acid per 100 g fresh weight (GA) equivalent after subtracting the contribution from ascorbic acid. Because ascorbic acid (a non-phenolic compound) reacts readily with Folin-Ciocal-teu reagents and contributes to phenolic content, each assay was carried out in triplicate.

Antioxidant capacity The antioxidant capacity of fresh mushroom was ana-lyzed on the base of determination of free radical-scaveng-ing effect of antioxidants on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical according to the procedure described by Elez-Martínez and Martín-Belloso (2007). Methanol was used as a solvent to study the antioxidants extraction from A. bisporus. Mushroom samples were centrifuged for 15 min at 4°C (Beckman Instruments Inc., Fullerton, California) and filtered through Whatman No. 1 filter paper. Aliquot of 0.01 mL of the supernatant was mixed with 3.9 mL of methanolic DPPH solution and 0.09 mL of distilled water. The homoge-nate was shaken vigorously and kept in the dark for 30 min. The absorption of the samples was measured with a CECIL CE 2021 spectrophotometer (Cecil Instruments Ltd., Cam-bridge, UK) at 515 nm for DPPH. The percentage of inhibition of the absorbance was calculated and plotted as a function of the concentration of Trolox for the standard reference data. The final DPPH value was calculated by using a calibration curve and the percentage of inhibition was determined.

Statistical analysisThe data were subjected to Analysis of Variance in SAS

(ver. 9. SAS, Inc., Cary, N.C.) and the means were separated using Tukey’s test.

Results and discussion

Effect of supplementing at casing on mushroom whiteness

There was a significant difference between supple-men-ted substrate and control for color values (Table 3). During the storage, decrease of the mushroom whiteness was observed for all mushrooms, control and treated. The L* value in control (0 g) decreased from 89.20 on day 1 to 71.06 on day 16. The amount of a* and b* values in con-trol substrate increased from 0.25 and 18.61 on day 1 to 4.23 and 34.09 on day 16, respectively (Figure 1). Indeed, the lowest amount of a* and b* value in days 8, 12 and 16 were obtained by 51 g corn (Figure 1). The brown-colored patches are a consequence of PPO activation, as a specific response to spoilage organisms such as Pseudomonas tolas-sii, leading to oxidation of phenolic compounds to form mel-anins (Soler et al., 1998). Whiteness of pileus and stipe is often used as important index of visible quality, since rapid discoloration occurs after harvest (Gormley, 1975).

Effect of supplementing at casing on water loss There was significant differences for weight loss in

supplemented and control button mushroom for weight loss (Table 3). Weight loss in controls and supplemented samples increased during the storage period. At the end of storage time, the weight losses of control (0 g) was sig-nificantly different from those observed in supplemented mushrooms except for 51 g corn (Figure 2). The weight loss is due to the evaporation of water from the fruit surface as a result of respiration and transpiration. Weight loss is one of the physiological parameters used as quality indicator in fruits and vegetables.

Effect of supplementation at casing on electrolyte leakage

The results showed significant differences for electro-lyte leakage (Table 3). Electrolyte leakage of mushrooms was lowered significantly by application of 51 g corn at




Figure 1. Effect of supplementing at casing on color (L*, a* and b* values) in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

8

Figure1.Effectofsupplementingatcasingoncolor(L*,a*andb*values)inAgaricusbisporusfruitbodiesduringstorageat4°C.Verticalbarsrepresentthestandarddeviationaboutthemean(r=3).

0.0010.0020.0030.0040.0050.0060.0070.0080.0090.00100.00

1 4 8 12 16

L*value

Storagetime(d)

controlSB17CR17SB34CR34SB51CR51

00.51

1.52

2.53

3.54

4.55

1 4 8 12 16

a*value

Storagetime(d)


0.005.0010.0015.0020.0025.0030.0035.0040.00

1 4 8 12 16

b*value

Storagetime(d)


Table 3. ANOVA effects due to supplementing at casing with ground corn and soybean seed at four levels (0, 17, 34 and 51 g) on color (L, a, b values), weight loss (WL) and electrolyte leakage rate (EL).

Source df WL (%)

EL (%) L* values a* values b* values

A 6 0.188** 0.689** 81.083** 2.786** 41.894**

Error (a) 12 0.052 0.162 0.426 0.063 0.198B 4 199.50** 10.481** 607.89** 27.93** 332.77**

a*b 24 0.044 ns 0.18** 6.499** 0.386** 5.434**

Error (B) 48 0.019 0.034 0.69 0.005 0.749CV – 4.86 5.72 8.8 17.15 2.65

** Signifi cant at P≤0.01, ANOVA.A: treatment; B: storage time; a*b: treatment * storage time.CV: coeffi cient of variation; df: degrees of freedom.




casing compared with control all days of storage. However, the substrates which were treated with 51 g soybean had higher electrolyte leakage than control at 4th, 8th and 12th days (Figure 3).

Electrolyte leakage is an index of the semipermeable properties of cell membranes, and a reduction in membrane integrity resulting from lipid peroxidation increases membrane leakage and enhances cell senescence (Hildebrand, 1989). Decreased rates of membrane lipid peroxidation and membrane leakage observed following treatment of V. volvacea and L. edodes fruit bodies with Co-60 irradiation (Ye et al., 2000) and calcium chloride (Li

et al., 2000), respectively, were accompanied by marked prolongation of postharvest mushroom freshness.

Effect of supplementing at casing on TSSTotal soluble solid (TSS) button mushroom significantly

affected by supplementation treatments (Table 4). Supple-mentation with corn and soybean (51 g) caused small de-crease in TSS compared with other treatments during the storage time. Non supplemented mushrooms had lowest TSS of day 1 to day 16 (Figure 4). Total soluble solid was earlier reported to be the major respiration substrate in A. bisporus during postharvest storage (Hammond and Nicho-

Figure 2. Effect of supplementing at casing on water loss in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

Figure 4. Effect of supplementing at casing on TSS in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

10

Figure 2. Effect of supplementing at casing on water loss in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.001.002.003.004.005.006.007.008.009.00

10.00

1 4 8 12 16

Weigh

t loss

(%)

Storage time (d)

controlSB 17CR 17SB 34CR 34SB 51CR 51

11

Figure 3. Effect of supplementing at casing on electrolyte leakage in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.00

1.00

2.00

3.00

4.00

5.00

6.00

1 4 8 12 16

Relat

ive le

akag

e rate

(%)

Storage time (d)


12

Figure 4. Effect of supplementing at casing on TSS in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

1 4 8 12 16

TSS (

°Brix

)

Storage time (d)


Figure 3. Effect of supplementing at casing on electrolyte leakage in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).




las, 1975), and steady decreases in TSS concentration were previously reported in fruit bodies stored at cold-temper-atures (Tseng and Mau, 1999). Sugars, protein, minerals, etc., constitute TSS of mushrooms. About 75–80% of TSS is sugars. The main sugar of A. bisporus is mannitol. Carbon supplied to the compost in oil supplementation at casing was utilized to synthesize mannitol and fatty acids (Holtz and Schisler, 1986).

Effect of supplementing at casing on vitamin C and phenol content

There was a significant difference between supple-mented and control mushroom for vitamin C and total

phenols (Table 4). In this study, supplementing also signifi-cantly enhanced total phenols content and reduced form of vitamin C (Figures 5 and 6). During days of storage, most reduced form vitamin C content observed from the soybean supplement (34 and 51 g). The highest amount of total phe-nol was produced by adding corn (51 g) to case soil. Indeed, total phenol was lowest in control in storage time (Figure 6). Several authors noted a decrease in vitamin C in vegeta-ble crops (Rai and Saxena, 1988; Salem, 1974). Changes in reduced ascorbic acid, according to the literature, are due to its serving as a radical scavenger. The possible reason for accelerated decrease of ascorbic acid in supplemented and non-supplemented samples might be enhanced respiration.

Figure 5. Effect of supplementing at casing on vitamin C in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

13

Figure 5. Effect of supplementing at casing on vitamin C in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.000.501.001.502.002.503.003.504.00

1 4 8 12 16

Redu

ced V

it C. (m

g 100

g-1fw

t)

Storage time (d)


14

Figure 6. Effect of supplementing at casing on total phenol in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0

50

100

150

200

250

1 4 8 12 16

Total

phen

ol (m

g 100

g-1f w

t )

Storage time (d)


Figure 6. Effect of supplementing at casing on total phenol in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

Table 4. ANOVA effects due to supplementing at casing with ground corn and soybean seed at four levels (0, 17, 34 and 51 g) on total soluble solid (TSS), vitamin C content, protein content, antioxidant capacity (AC) and total phenolic compounds.

Source df TSS(g 100 g-1 f.wt)

Vitamin C(mg 100 g-1 f.wt)

Protein(g 100 g-1 f.wt)

AC(mmol kg-1 f.wt)

Total phenol(mg 100 g-1 f.wt )

A 6 1.741** 1.496** 2.199** 3.804** 10105.59**

Error (a) 12 0.048 0.09 0.061 0.019 87.21B 4 8.278* 4.577** 3.968** 3.279** 40301.0**

a*b 24 0.037* 0.035** 0.018* 0.069** 140.71**

Error (B) 48 0.016 0.015 0.02 0.005 45.60CV – 4.27 3.11 7.89 4.21 3.30

** Signifi cant at P≤0.01, ANOVA.CV: coeffi cient of variation; df: degrees of freedom; f.wt: fresh weight.




Effect of supplementing at casing on protein contentSupplementing significantly affected on protein con-

tent of button mushroom (Table 4). The amounts of protein continually decreased from day 1 to day 16. The highest protein in storage times of 1, 4, 8, 12 and 16 days in mush-rooms was due to the use of soybean (51 g) with case soil. At any of the time periods during the study, significant difference was observed between supplemented and non-supplemented mushrooms in protein content (Figure 7). Murr et al. (1975) had pointed that protein degradation, as indicated by protease activity and the level of free amino acid in the tissue, increased during postharvest maturation of the mushroom, and they assumed that the assimilation may function as the source of C or N. A decline in soluble protein concentration is considered to be an important in-dicator of tissue senescence (Burton et al., 1997).

Effect of supplementing at casing on antioxidant capacity

Antioxidant is another property that is significantly af-fected by supplementing treatments (Table 4). The lowest antioxidant capacity (AC) was found in control. Except day 16, during storage time the substrate which treated with soybean (34 g) caused the highest antioxidant capacity of mushrooms compared with other supplements (Figure 8).

Major antioxidants in fresh vegetable are phenolic acids and flavonoids (Hanasaki et al., 1994). Phenolics, such as tannic acid and gallic acid, have high antioxidant activity (Pulido et al., 2000). Increased antioxidant capacity after the supplementation with soybean could also be related to high content of polyphenolic isoflavonoids such as genistein, genistin, daidzein, daidzin, formononetin, and afrormosin in soybean (Lachman et al., 1990).

ConclusionIn conclusion, supplementing substrate at casing is a

relatively easy and low-cost cultural practice that may be successfully used to enhance yields, BE, quality and max-imize utilization of substrate. Since microbial populations in casing material are important in promoting fructifica-tion in A. bisporus, supplementing at casing can also affect microorganism populations. According to this study, sup-plementing with 34 g soybean and 51 g corn improved the color and some quality indices of A. bisporus more than control and other treatments. Consequently, we can rec-ommend supplementing with 34 g soybean and 51 g corn at casing stage as a good practice to increase the shelf-life. Our results suggest supplementing also increased nutritive values by promoting production of antioxidants.

15

Figure 7. Effect of supplementing at casing on protein content in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

1 4 8 12 16

Prote

in (m

g 100

g-1fw

t)

Storage time (d)


16

Figure 8. Effect of supplementing at casing on antioxidant capacity (AC) in Agaricusbisporusfruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

0.000.501.001.502.002.503.003.504.004.50

1 4 8 12 16

AC (m

mol k

g-1f w

t)

Storage time (d)


Figure 8. Effect of supplementing at casing on antioxidant capacity (AC) in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).

Figure 7. Effect of supplementing at casing on protein content in Agaricus bisporus fruit bodies during storage at 4°C. Vertical bars represent the standard deviation about the mean (r=3).




AcknowledgmentsAuthors acknowledge the support of the University of

Guilan, Iran.

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Received: Dec. 5, 2014Accepted: Apr. 24, 2015

Addresses of authors: Mohammad Adibian1 and Yaqvob Mami2,* 1. Higher Educational Complex of Saravan, Iran2. Department of Horticulture Science, Faculty of Agricul- ture, University of Guilan, Tehran Road (km 6) Rasht, 1841, Iran* Corresponding author; E-mail: [email protected] Tel.: +989116491791, Fax: +981316690281


mushroom supplement added to casing to improve postharvest ... · this project was done to study...

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